Characterization of Glycosylated Aroma Compounds in Tannat Grapes and Feasibility of the Near Infrared Spectroscopy Application for Their Prediction

The objective measure of grape quality is an important requirement to enhance wine quality. Particularly, the quantitation of glycosylated aroma compounds could be a useful index for winemakers. In the present work, we evaluated the bound compounds profile on Tannat grapes, and the potential of near infrared (NIR) spectroscopy coupled to chemometric techniques to determine the concentration of the different glycosylated aroma compounds present in this grape variety. The results showed phenols and norisoprenoids as the quantitative most important group of compounds, representing almost 80 % of the total glycosidic components present in Tannat grapes. The glycosidic form of ethyl-beta-(4-hydroxy-3-methoxy-phenyl)-propionate was identified for the first time in grapes. The results suggested NIR technique as a screening tool for a fast analysis of the grape aroma potential. The application of such methodology would be ideal for fast grape screening purposes, contributing to the winemaking decisions, classification of the fruit, and perhaps maturity monitoring.